As it is known, automotive taillights and the like usually comprise: a substantially basin-shaped and rigid rear body, which is structured to be stably fitted into a compartment especially formed in the rear part of the bodywork of the vehicle; a front half-shell that closes the mouth of the rear body so as to surface from the bodywork of the vehicle, and is usually provided with a plurality of transparent or semi-transparent portions, usually with different colour to one another; and a series of lighting assemblies that are located inside the rear body, each immediately underneath a respective transparent or semi-transparent portion of the front half-shell, so as to backlight the superjacent transparent or semi-transparent portion of the front half-shell.
Over the last few years, some car manufacturers have chosen to equip their newest car models with taillights in which the front half-shell is provided with one or more large-sized transparent or semi-transparent portions.
The lighting assemblies designed to backlight the large-sized transparent or semi-transparent portions generally comprise: a light-guide plate which is made of a photoconductive material and extends inside the rear body with the front face skimming over the transparent or semi-transparent portion to be backlighted, substantially over the entire extension of the same transparent or semi-transparent portion; and a series of LEDs (acronym for Light Emitting Diode), which are adjacent to and immediately face at least a lateral sidewall of the light-guide plate, so as to direct the light produced directly into the body of the light-guide plate. Said light than travels inside the body of the light-guide plate through total internal reflection and comes out of the front face of the light-guide plate directed towards the front half-shell, so that it can backlight the superjacent transparent or semi-transparent portion of the half-shell.
Unfortunately, in order to backlight the corresponding transparent or semi-transparent portion of the half-shell in a sufficiently uniform manner, the lighting assemblies described above need a large number of LEDs properly spaced apart from one another along the entire length of the lateral sidewall of the light-guide device, with all the problems that this entails. These problems are furthermore intensified if the LEDs have to be placed along two or more lateral sidewalls of the light-guide plate.
Said LEDs, in fact, are relatively expensive components and their cost significantly affects the total manufacturing costs of an automotive lighting unit.
In addition, an electronic board housing the LEDs necessarily must be accommodated in the rear body together with the power supply and control circuits, thus taking up a large space and preventing to reduce the dimensions of the taillight beyond a given limit.
Finally, during operation, the LEDs produce a significant quantity of heat that necessarily must be dissipated outwards, for example through large radiant surfaces made of copper and placed on the electronic board at the expense of the total dimensions of the board itself.